Quantum-Dots Light-Emitting Devices Based on Exciton Harvesting Layers

Quantum dot light-emitting diodes (QLEDs) have emerged as a promising technology for display and lighting applications due to their high color purity, tunable emission wavelengths, and solution processability. However, carrier imbalance arising from differences in injection barriers and mobilities between electrons and holes remains a significant challenge, leading to charge accumulation or leakage and resulting in performance losses. To address these issues, exciton harvesting layers (EHLs) have recently gained attention as an effective and targeted strategy. This review presents a comprehensive overview of the EHL concept and its development in QLEDs. We begin by introducing the fundamental properties of quantum dots (QDs) and the working principles of QLEDs, followed by a discussion of the applicability of the EHL strategy. We then detail the mechanisms of energy transfer within EHL and between EHL and QDs, as well as its optimization approaches. Subsequently, we summarize the application of EHLs in QLEDs and the corresponding improvements in device performance. Finally, we highlight current challenges and future research directions of the EHL strategy.